From mboxrd@z Thu Jan  1 00:00:00 1970
From: Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH 13/36] dt-bindings: arm: Convert PMU binding to
 json-schema
Date: Thu, 8 Nov 2018 15:54:31 +0000
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To: Rob Herring <robh@kernel.org>, Will Deacon <will.deacon@arm.com>, Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Mark Rutland <mark.rutland@arm.com>, devicetree@vger.kernel.org, Kumar Gala <kumar.gala@linaro.org>, Grant Likely <glikely@secretlab.ca>, Arnd Bergmann <arnd@arndb.de>, Tom Rini <trini@konsulko.com>, Frank Rowand <frowand.list@gmail.com>, Linus Walleij <linus.walleij@linaro.org>, Pantelis Antoniou <pantelis.antoniou@konsulko.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Bjorn Andersson <bjorn.andersson@linaro.org>, Mark Brown <broonie@kernel.org>, Geert Uytterhoeven <geert@linux-m68k.org>, Jonathan Cameron <jic23@kernel.org>, Olof Johansson <olof@lixom.net>, linuxppc-dev <linuxppc-dev@lists.ozlabs.org>, "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" <linux-arm-kernel@lists.infradead.org>
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On 01/11/2018 19:32, Rob Herring wrote:
> On Tue, Oct 9, 2018 at 6:57 AM Will Deacon <will.deacon@arm.com> wrote:
>>
>> Hi Rob,
>>
>> On Fri, Oct 05, 2018 at 11:58:25AM -0500, Rob Herring wrote:
>>> Convert ARM PMU binding to DT schema format using json-schema.
>>>
>>> Cc: Will Deacon <will.deacon@arm.com>
>>> Cc: Mark Rutland <mark.rutland@arm.com>
>>> Cc: linux-arm-kernel@lists.infradead.org
>>> Cc: devicetree@vger.kernel.org
>>> Signed-off-by: Rob Herring <robh@kernel.org>
>>> ---
>>>   Documentation/devicetree/bindings/arm/pmu.txt | 70 --------------
>>>   .../devicetree/bindings/arm/pmu.yaml          | 96 +++++++++++++++++++
>>>   2 files changed, 96 insertions(+), 70 deletions(-)
>>>   delete mode 100644 Documentation/devicetree/bindings/arm/pmu.txt
>>>   create mode 100644 Documentation/devicetree/bindings/arm/pmu.yaml
>>
>> [...]
>>
>>> -- interrupts : 1 combined interrupt or 1 per core. If the interrupt is a per-cpu
>>> -               interrupt (PPI) then 1 interrupt should be specified.
>>
>> [...]
>>
>>> +  interrupts:
>>> +    oneOf:
>>> +      - maxItems: 1
>>> +      - minItems: 2
>>> +        maxItems: 8
>>> +        description: 1 interrupt per core.
>>> +
>>> +  interrupts-extended:
>>> +    $ref: '#/properties/interrupts'
>>
>> This seems like a semantic different between the two representations, or am
>> I missing something here? Specifically, both the introduction of
>> interrupts-extended and also dropping any mention of using a single per-cpu
>> interrupt (the single combined case is no longer support by Linux; not sure
>> if you want to keep it in the binding).
> 
> In regards to no support for the single combined interrupt, it looks
> like Marvell Armada SoCs at least (armada-375 is what I'm looking at)
> have only a single interrupt. Though the interrupt gets routed to MPIC
> which then has a GIC PPI. So it isn't supported or happens to work
> still since it is a PPI?

Well, the description of the MPIC in the Armada XP functional spec says:

"Interrupt sources ID0–ID28 are private events per CPU. Thus, each 
processor has a different set of events map interrupts ID0–ID28."

Odd grammar aside, that would seem to imply that <&mpic 3> is a per-cpu 
interrupt itself, thus AFAICS so long as it's cascaded to a GIC PPI and 
not an SPI then there's no issue there.

Robin.